Waste reduction decreases rat activity from peri-urban environment

Abstract

Globally, species in the genus Rattus (specifically Rattus rattus and Rattus norvegicus), are some of the most influential invasive taxa due to their high rates of competitive exclusion and large dietary breadth. However, the specific foraging strategies of urban-adjacent populations remain largely unknown. We examined Rattus spp. dependency on human food supplementation in a population on adjacent non-developed (or peri-urban) land. Via linear regression modeling, we measured rodent activity changes between native and invasive species before and after a decrease in human supplementation due to the COVID-19 lockdown in Santa Cruz, California, USA. We documented invasive rat activity via camera traps in normal (pre-COVID lockdown) conditions near dining halls and similar waste sources, and again under COVID lockdown conditions when sources of human supplementation were drastically decreased. After 120 trap nights we found a significant decrease (p < 0.001) in Rattus activity after the removal of human refuse, while native small mammal activity remained unchanged (p = 0.1). These results have strong conservation implications, as they support the hypothesis that proper waste management is an effective, less-invasive form of population control over conventional rodenticides.